Ex-Utahn Spurns Teaching Career To Become Ace Film Producer David Hempstcad might be one of the youngest, most popular popular professors at the University of Michigan right now If It hadn't been for two things— money and a girl. As It Is, at the age of 32, he's struggling along In Hollywood as one of the movie industry's top producers. And what will it get him ? A fortune, probably. probably. ' He already has the girl. He also has already garnered considerable kudos for producing auch outstanding pictures as "Kitty Foyle," which last year won the academy award for Ginger Rogers. Just lately he wound up production production on his second picture nt RKO studio, "Joan of T"aris." of which more later. This is- a career story, isn't it, and .don't they have to begin at the beginning? beginning?